Calendar
The examples and perspective in this article deal primarily with Eurasia and the Near East and do not represent a worldwide view of the subject. (September 2022) |
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A calendar is a system of organizing
Periods in a calendar (such as years and months) are usually, though not necessarily, synchronized with the cycle of the
Etymology
The term calendar is taken from kalendae,[7][8] the term for the first day of the month in the Roman calendar, related to the verb calare 'to call out', referring to the "calling" of the new moon when it was first seen.[9] Latin calendarium meant 'account book, register' (as accounts were settled and debts were collected on the calends of each month).[10] The Latin term was adopted in Old French as calendier and from there in Middle English as calender by the 13th century (the spelling calendar is early modern).[10]
History
The course of the Sun and the Moon are the most salient regularly recurring natural events useful for
The first recorded physical calendars, dependent on the development of
During the Vedic period India developed a sophisticated timekeeping methodology and calendars for Vedic rituals.[13] According to Yukio Ohashi, the Vedanga calendar in ancient India was based on astronomical studies during the Vedic Period and was not derived from other cultures.[14]
A large number of calendar systems in the Ancient Near East were based on the Babylonian calendar dating from the Iron Age,[15] among them the calendar system of the Persian Empire, which in turn gave rise to the Zoroastrian calendar and the Hebrew calendar.[16][17]
A great number of
Calendars in antiquity were
The
The
There have been several modern proposals for reform of the modern calendar, such as the World Calendar, the International Fixed Calendar, the Holocene calendar, and the Hanke–Henry Permanent Calendar. Such ideas are mooted from time to time, but have failed to gain traction because of the loss of continuity and the massive upheaval that implementing them would involve, as well as their effect on cycles of religious activity.
Systems
A full calendar system has a different calendar date for every day.[20][21] Thus the week cycle is by itself not a full calendar system;[22] neither is a system to name the days within a year without a system for identifying the years.
The simplest calendar system just counts time periods from a reference date.
Other calendars have one (or multiple) larger units of time.
Calendars that contain one level of cycles:
- week and weekday – this system (without year, the week number keeps on increasing) is not very common
- year and ordinal date within the year, e.g., the ISO 8601 ordinal date system
Calendars with two levels of cycles:
- year, month, and day – most systems, including the Gregorian calendar (and its very similar predecessor, the Julian calendar), the Islamic calendar, the Solar Hijri calendar and the Hebrew calendar
- year, week, and weekday – e.g., the ISO week date
Cycles can be synchronized with periodic phenomena:
- Lunar calendars are synchronized to the motion of the Moon (lunar phases); an example is the Islamic calendar.
- Persian calendar.
- Lunisolar calendars are based on a combination of both solar and lunar reckonings; examples include the traditional calendar of China, the Hindu calendar in India and Nepal, and the Hebrew calendar.
- The week cycle is an example of one that is not synchronized to any external phenomenon (although it may have been derived from lunar phases, beginning anew every month).
Very commonly a calendar includes more than one type of cycle or has both cyclic and non-cyclic elements.
Most calendars incorporate more complex cycles. For example, the vast majority of them track years, months, weeks and days. The seven-day week is practically universal, though its use varies. It has run uninterrupted for millennia.[24]
Solar
Solar calendars assign a date to each solar day.[25] A day may consist of the period between sunrise and sunset, with a following period of night, or it may be a period between successive events such as two sunsets.[26][27] The length of the interval between two such successive events may be allowed to vary slightly during the year, or it may be averaged into a mean solar day. Other types of calendar may also use a solar day.
The Egyptians appear to have been the first to develop a solar calendar,[28] using as a fixed point the annual sunrise reappearance of the Dog Star—Sirius, or Sothis—in the eastern sky, which coincided with the annual flooding of the Nile River.[29][30][31] They built a calendar with 365 days, divided into 12 months of 30 days each, with 5 extra days at the end of the year. However, they didn't include the extra bit of time in each year, and this caused their calendar to slowly become inaccurate.[32]
Lunar
Not all calendars use the solar year as a unit. A lunar calendar is one in which days are numbered within each lunar phase cycle. Because the length of the lunar month is not an even fraction of the length of the tropical year, a purely lunar calendar quickly drifts against the seasons, which do not vary much near the equator. It does, however, stay constant with respect to other phenomena, notably tides. An example is the Islamic calendar. Alexander Marshack, in a controversial reading,[33] believed that marks on a bone baton (c. 25,000 BC) represented a lunar calendar. Other marked bones may also represent lunar calendars. Similarly, Michael Rappenglueck believes that marks on a 15,000-year-old cave painting represent a lunar calendar.[34]
Lunisolar
A lunisolar calendar is a lunar calendar that compensates by adding an extra month as needed to realign the months with the seasons. Prominent examples of lunisolar calendar are Hindu calendar and Buddhist calendar that are popular in South Asia and Southeast Asia. Another example is the Hebrew calendar, which uses a 19-year cycle.
Subdivisions
Nearly all calendar systems group consecutive days into "months" and also into "years". In a solar calendar a year approximates Earth's tropical year (that is, the time it takes for a complete cycle of seasons), traditionally used to facilitate the planning of agricultural activities. In a lunar calendar, the month approximates the cycle of the moon phase. Consecutive days may be grouped into other periods such as the week.
Because the number of days in the tropical year is not a whole number, a solar calendar must have a different number of days in different years. This may be handled, for example, by adding an extra day in leap years. The same applies to months in a lunar calendar and also the number of months in a year in a lunisolar calendar. This is generally known as intercalation. Even if a calendar is solar, but not lunar, the year cannot be divided entirely into months that never vary in length.
Cultures may define other units of time, such as the week, for the purpose of scheduling regular activities that do not easily coincide with months or years. Many cultures use different baselines for their calendars' starting years. Historically, several countries have based their calendars on
Other types
Arithmetical and astronomical
An astronomical calendar is based on ongoing observation; examples are the religious Islamic calendar and the old religious Jewish calendar in the time of the Second Temple. Such a calendar is also referred to as an observation-based calendar. The advantage of such a calendar is that it is perfectly and perpetually accurate. The disadvantage is that working out when a particular date would occur is difficult.
An arithmetic calendar is one that is based on a strict set of rules; an example is the current
Other variants
The early Roman calendar, created during the reign of Romulus, lumped the 61 days of the winter period them together as simply "winter."[35] Over time, this period became January and February; through further changes over time (including the creation of the Julian calendar) this calendar became the modern Gregorian calendar, introduced in the 1570s.[36][37]
Usage
The primary practical use of a calendar is to identify days: to be informed about or to agree on a future event and to record an event that has happened. Days may be significant for agricultural, civil, religious, or social reasons. For example, a calendar provides a way to determine when to start planting or harvesting, which days are
Calendars are also used as part of a complete
Gregorian
The
The calendar was introduced in 1582 as a refinement to the
The
Religious
The most important use of pre-modern calendars is keeping track of the liturgical year and the observation of religious feast days.
While the Gregorian calendar is itself historically motivated to the calculation of the
Western Christian liturgical calendars are based on the cycle of the Roman Rite of the Catholic Church and generally include the liturgical seasons of Advent, Christmas, Ordinary Time (Time after Epiphany), Lent, Easter, and Ordinary Time (Time after Pentecost). Some Christian calendars do not include Ordinary Time and every day falls into a denominated season.
The
Various
The Buddhist calendar and the traditional lunisolar calendars of Cambodia, Laos, Myanmar, Sri Lanka and Thailand are also based on an older version of the Hindu calendar.
Most of the Hindu calendars are inherited from a system first enunciated in
The Hebrew calendar is used by Jews worldwide for religious and cultural affairs, also influences civil matters in Israel (such as national holidays) and can be used business dealings (such as for the dating of cheques).[43]
Followers of the Baháʼí Faith use the Baháʼí calendar. The Baháʼí Calendar, also known as the Badi Calendar was first established by the Bab in the Kitab-i-Asma. The Baháʼí Calendar is also purely a solar calendar and comprises 19 months each having nineteen days.
National
The Chinese, Hebrew, Hindu, and Julian calendars are widely used for religious and social purposes.
The
Fiscal
A fiscal calendar generally means the accounting year of a government or a business. It is used for budgeting, keeping accounts, and taxation. It is a set of 12 months that may start at any date in a year. The US government's fiscal year starts on 1 October and ends on 30 September. The government of India's fiscal year starts on 1 April and ends on 31 March. Small traditional businesses in India start the fiscal year on Diwali festival and end the day before the next year's Diwali festival.
In accounting (and particularly accounting software), a fiscal calendar (such as a 4/4/5 calendar) fixes each month at a specific number of weeks to facilitate comparisons from month to month and year to year. January always has exactly 4 weeks (Sunday through Saturday), February has 4 weeks, March has 5 weeks, etc. Note that this calendar will normally need to add a 53rd week to every 5th or 6th year, which might be added to December or might not be, depending on how the organization uses those dates. There exists an international standard way to do this (the ISO week). The ISO week starts on a Monday and ends on a Sunday. Week 1 is always the week that contains 4 January in the Gregorian calendar.
Formats
The term calendar applies not only to a given scheme of timekeeping but also to a specific record or device displaying such a scheme, for example, an
In a paper calendar, one or two sheets can show a single day, a week, a month, or a year. If a sheet is for a single day, it easily shows the date and the weekday. If a sheet is for multiple days it shows a conversion table to convert from weekday to date and back. With a special pointing device, or by crossing out past days, it may indicate the current date and weekday. This is the most common usage of the word.
In the US Sunday is considered the first day of the week and so appears on the far left and Saturday the last day of the week appearing on the far right. In Britain, the weekend may appear at the end of the week so the first day is Monday and the last day is Sunday.[citation needed] The US calendar display is also used in Britain.
It is common to display the Gregorian calendar in separate monthly grids of seven columns (from Monday to Sunday, or Sunday to Saturday depending on which day is considered to start the week – this varies according to country)[citation needed] and five to six rows (or rarely, four rows when the month of February contains 28 days in common years beginning on the first day of the week), with the day of the month numbered in each cell, beginning with 1. The sixth row is sometimes eliminated by marking 23/30 and 24/31 together as necessary.
When working with weeks rather than months, a continuous format is sometimes more convenient, where no blank cells are inserted to ensure that the first day of a new month begins on a fresh row.
Software
Calendaring software provides users with an electronic version of a calendar, and may additionally provide an appointment book, address book, or contact list. Calendaring is a standard feature of many
See also
- General Roman Calendar
- List of calendars
- Advent calendar
- Calendar reform
- Calendrical calculation
- Docket (court)
- History of calendars
- Horology
- List of international common standards
- List of unofficial observances by date
- Real-time clock (RTC), which underlies the Calendar software on modern computers.
- Unit of time
References
Citations
- ^ "Calendars and their History". eclipse.gsfc.nasa.gov. Retrieved 12 March 2024.
- ISBN 978-981-13-0547-4.
- ISBN 978-0-7978-0222-3.
- ^ "Do menstrual and lunar cycles synchronize? What scientists say". www.medicalnewstoday.com. 12 February 2021. Retrieved 12 March 2024.
- ^ "Introduction to Calendars". aa.usno.navy.mil. Retrieved 12 March 2024.
- ^ "History – Ancient Egyptian Calendar" (PDF). Retrieved 12 March 2024.
- ISBN 978-1-257-10758-2.
- ISBN 978-1-57859-246-3.
- ^ New Shorter Oxford English Dictionary
- ^ ISBN 978-1-5457-4730-8.
- ^ "Religion in the Etruscan Period" in Roman Religion Archived 15 October 2015 at the Wayback Machine in the Encyclopædia Britannica
- from the original on 9 April 2023. Retrieved 16 March 2021.
- ISBN 978-0-691-12067-6.
- ISBN 978-0-7923-5556-4. Archivedfrom the original on 11 January 2023. Retrieved 12 March 2021.
- ISBN 978-0-684-19279-6.
- ^ "Egyptians celebrate new Egyptian year on September 11". EgyptToday. 12 September 2021. Retrieved 12 March 2024.
- ISBN 978-1-5457-4730-8.
- ^ "Calendar - The Early Roman Calendar". Encyclopedia Britannica. 24 December 2020. Archived from the original on 4 January 2021. Retrieved 19 January 2021.
- ^ "The History of the Calendar". Archived from the original on 2 December 2020.
- ISBN 978-81-940294-3-4.
- ISBN 978-81-939356-9-9.
- ISBN 978-81-939356-9-9.
- ISBN 978-81-939356-9-9.
- ^ Zerubavel 1985.
- ^ "Introduction to Calendars". aa.usno.navy.mil. Retrieved 12 March 2024.
- ^ The Jurist. S. Sweet. 1861. p. 983.
- ISBN 978-0-7387-6721-5.
- ^ "Solar calendar | Ancient Egypt, Mayan, Aztec | Britannica". www.britannica.com. Retrieved 12 March 2024.
- ISBN 978-0-85229-529-8.
- ISBN 979-8-216-14241-6.
- ISBN 978-0-19-064901-2.
- ^ "Solar calendar | chronology | Britannica".
- ^ James Elkins, Our beautiful, dry, and distant texts (1998) 63ff.
- ^ "Oldest lunar calendar identified". BBC News. 16 October 2000. Archived from the original on 11 February 2021. Retrieved 14 March 2013.
- ^ Jones, Derek (8 March 2018). "Roman Calendar". editions.covecollective.org. Retrieved 18 March 2024.
- ^ "Who Decided January 1st Is the New Year?". TIME. 29 December 2023. Retrieved 18 March 2024.
- ^ Kelechava, Brad (11 February 2016). "History of the Standard Gregorian Calendar". The ANSI Blog. Retrieved 18 March 2024.
- ^ a b Blackburn & Holford-Strevens 2003, pp. 682–683.
- ^ Blackburn & Holford-Strevens 2003, pp. 817–820.
- ^ Dershowitz & Reingold 2008, pp. 47, 187.
- ^ Blackburn & Holford-Strevens 2003, pp. 682–689.
- ^ Blackburn & Holford-Strevens 2003, Chapter: "Christian Chronology".
- ^ "About the Hebrew Calendar | Yale University Library". web.library.yale.edu. Retrieved 18 March 2024.
Sources
- "calendar", American Heritage Dictionary (5th ed.), 2017
- Birashk, Ahmad (1993), A Comparative Calendar of the Iranian, Muslim Lunar, and Christian Eras for Three Thousand Years, Mazda Publishers, ISBN 978-0-939214-95-2
- Björnsson, Árni (1995) [1977], High Days and Holidays in Iceland, Reykjavík: Mál og menning, OCLC 186511596
- Blackburn, Bonnie; Holford-Strevens, Leofranc (2003) [1999], The Oxford Companion to the Year (corrected reprinting of 1st ed.), Oxford University Press
- ISBN 978-0-521-70238-6
- Doggett, L.E. (1992), "Calendars", in Seidelmann, P. Kenneth (ed.), Explanatory Supplement to the Astronomical Almanac, University Science Books, ISBN 978-0-935702-68-2
- Richards, E.G. (1998), Mapping Time, the calendar and its history, Oxford University Press, ISBN 978-0-19-850413-9
- Rose, Lynn E. (1999), Sun, Moon, and Sothis, Kronos Press, ISBN 978-0-917994-15-9
- Schuh, Dieter (1973), Untersuchungen zur Geschichte der Tibetischen Kalenderrechnung (in German), Wiesbaden: Franz Steiner Verlag, OCLC 1150484
- Spier, Arthur (1986), The Comprehensive Hebrew Calendar, Feldheim Publishers, ISBN 978-0-87306-398-2
- Zerubavel, Eviatar (1985), The Seven Day Circle: The History and Meaning of the Week, University of Chicago Press, ISBN 978-0-226-98165-9
Further reading
- Fraser, Julius Thomas (1987), Time, the Familiar Stranger (illustrated ed.), Amherst: Univ of Massachusetts Press, OCLC 15790499
- Whitrow, Gerald James (2003), What is Time?, Oxford: Oxford University Press, OCLC 265440481
- C.K, Raju (2003), The Eleven Pictures of Time, SAGE Publications Pvt. Ltd, ISBN 978-0-7619-9624-8
- C.K, Raju (1994), Time: Towards a Consistent Theory, Springer, ISBN 978-0-7923-3103-2
External links
- Encyclopædia Britannica. Vol. IV (9th ed.). 1878. pp. 664–682. .
- Encyclopædia Britannica. Vol. 4 (11th ed.). 1911. p. 987-1004. .
- Encyclopedia Americana. 1920. .
- Calendar converter, including all major civil, religious and technical calendars.